This invention relates generally to sound equipment systems of the type provided with a sound source, an amplifier, and one or more loudspeakers (hereinafter referred to as speakers). More particularly the invention relates to a sound equipment system of this type wherein either of low-impedance speakers and high-impedance speakers can be selectively used.
In large buildings such as schools, hospitals and department stores and in public facilities, emergency sound broadcasting equipment as prescribed by the regulations concerning disasters of local law are installed. Ordinarily, for this emergency sound broadcasting equipment, a sound equipment system of high-impedance type is adopted. In many cases this sound equipment system is utilized to broadcast music.
In residences or homes, in general, stereo sound systems of low-impedance type are widely used. By these systems, stereo music of good sound quality can be readily reproduced.
In the design of public-address systems of the high-impedance type widely adopted as emergency broadcasting equipment in places such as large buildings and public facilities as mentioned above, top priority is given to characteristics such as sound pressure and durability so as to meet the safety standards prescribed by the local law. For this reason, these systems are ordinarily of the monaural type, and to date not much consideration has been given to the various characteristics relating to sound quality. Therefore, in the case where a broadcasting system of this monaural high-impedance type is used for musical reproduction, it is difficult to obtain good sound quality.
On the other hand, the installing of a stereo sound system of low-impedance type generally used in homes in a spacious building gives rise to problems in that demerits relating to function and installation increase. More specifically, in many large buildings, stereo music can be listened to in quiet environments such as individual or private rooms and other spaces such as corridors or hallways. Such places however are generally remote from the sound source and the amplifier as, for example, in a building with several floors. When a sound equipment system capable of reproducing stereo music at each of these places in such a building is to be organized and installed, the installing of the wiring of this system of low-impedance type becomes complicated. In addition, the length of the speaker cables is also subject to limitation.